A hydraulic control system for an engine supplies oil to various engine components and may also include oil control valves to control oil under pressure that may be used to, for example, switch latch pins in switching lifters, switching rocker arms, and switching lash adjusters in engine valve train systems. Valve actuation systems include, but are not limited to, valve deactivation and variable valve lift systems.
Valve lifters are engine components that transfer cam motion which controls the opening and closing of exhaust and intake valves in an engine. Lash adjusters and rocker arms may also be used to change lift profiles on exhaust and intake valves in an engine. In addition to varying valve lift, variable valve actuation systems may selectively activate or deactivate the engine valve. The engine valves are deactivated or locked out to disable operation of some cylinders in an engine when power demands on an engine are reduced. By deactivating cylinders, fuel efficiency of an engine may be improved.
Engine oil control valves must operate with minimum response times to maximize engine efficiency and increase engine durability. Latch pin switching response times include latch pin activation response times and deactivation response times. In variable valve actuation systems, the limited time window for valve actuation is critical and must be minimized. Additionally, as the flow rate and pressures within the system changes due to temperature and engine speed to actuate the valves, the oil flow rate to all the system components is similarly affected.